The treatment of the cerebral glioma continues to challenge neurosurgeons and basic scientists. The lack of major success with chemotherapy and radiation therapy has spurred further investigation into the biology of this tumor and host reactions to it. Much of this research has centred upon evaluation of tumor cell antigenicity and the cellular immune responses to the glioma. Contrary to previous considerations evidence suggests that astrocytes, glioma cells and tumor endothelial cells may all have pivotal roles in the initiation and prolongation of both local and systemic immune responses to the tumor. In this review we will discuss the immunobiology of the glioma with specific reference to the interactions between the tumor and the host immune system. In addition, ideas for potential therapeutic manipulation of the host-glioma immune interactions will be reviewed stressing potential pitfalls and risks.